Locate it (in C:\) and double-click on it (launch it). You'll recieve a prompt similar to: "Do you wish to merge the information into the registry?". Answer yes and wait for a message to appear similar to "Merged Succesfully".
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Close all (browser) windows & rescan with hijackthis. When the scan is finished place a check in the box to the left of the following entries & click 'fix checked' :